The refrigerant in an automotive air conditioning system gradually can become contaminated with lubricant from the air conditioning compressor, chemicals such as certain hexane derivatives, particulate matter, moisture, and other contaminates. Commercial recycling systems for removing such contaminates from air conditioning refrigerant to reclaim clean reusable refrigerant are known. U.S. Pat. Nos. 5,575,833; 6,244,055; and 5,761,924 disclose examples of such recycling systems and are hereby incorporated by reference as if fully set forth herein. In addition, refrigerant recycling systems are available to automotive service providers from several companies including, for example, RTI Technologies, Inc. of York, Pa. RTI's website is www.rtitech.com and the contents of the website regarding refrigerant recycling systems is hereby incorporated by reference as background information.
These existing systems have been satisfactory in the past, in part because there generally was only one lubricating oil used, there were no chemical leak locating dies in the refrigerant that were incompatible with the next compressors refrigerant charge, and there were no sealants that were incompatible with both the oils-dies and the recycling equipment used. Today, however, contaminated refrigerant may contain most or all of these contaminants, which must be removed or separated from the refrigerant by a recycling system. Some of these components, if not removed, impede the removal of other contaminates.
An oil separator is a component of a modern refrigerant recycling system that typically is not the first thing encountered by contaminated refrigerant delivered to the system. The purpose of an oil separator is to separate lubricating oils (lubricants) from the refrigerant. If the lubricant is not removed from the refrigerant, the lubricant, which is an oily substance, will tend to clog and gunk up valves, filters, filter bed media, and other components of the recycling system. A typical oil separator takes the form of a canister into which contaminated refrigerant is expelled through an inlet. As the refrigerant is expelled, it vaporizes within the canister. However, since the lubricant is less volatile than the refrigerant, it does not tend to vaporize but instead generally settles to the bottom of the oil separator canister, from where it can be drained off. The remaining refrigerant vapor then is ejected from the oil separator through an outlet and delivered to downstream components of the recycling system for further recovery processes. In one commercially available oil separator, the contaminated refrigerant is ejected into the oil separator canister through a porous filter element, which “sprays” the refrigerant into the canister in the form of a fine mist to enhance and speed up the vaporization of the refrigerant in the canister.
While prior art oil separators have performed relatively well for removing lubricants from contaminated refrigerant, they nevertheless have exhibited certain shortcomings. For example, although most of the lubricant within contaminated refrigerant precipitates to the bottom of the oil separator when the refrigerant vaporizes in the container, a small percentage of the lubricant takes the form of a fine rarified mist. This lubricant mist is then entrained in the refrigerant vapor and moves out of the oil separator and downstream where it eventually still clogs valves and other components of the recycling system. Other contaminates, such as Hexane and Hexane derivatives also may be present in the form of a fine mist. Traditional oil separators generally have removed very little of these hexane and other contaminates in a refrigerant stream.
Many modern refrigerant recycling machines include a reservoir in which clean refrigerant that has been recovered with the machine is collected. When an entire charge of refrigerant from an automotive air conditioning system has been cleaned and collected in the reservoir, the clean refrigerant typically is pumped back into the automotive air conditioning system through the same hose used to draw it out of the air conditioning system, all without disconnecting the hose. In this process, the cleaned refrigerant sometimes is pumped back through an oil separator. Since, as discussed above, lubricant originally dissolved in the refrigerant has been collected in the oil separator, some of this collected lubricant can again be entrained in, and re-contaminate, the cleaned refrigerant stream as it passes in reverse direction through the oil separator. Clearly, such re-contamination is highly undesirable.
Accordingly, there exists a need for an oil separator for a refrigerant recycling system that removes virtually 100% of lubricant from a contaminated stream of air conditioning refrigerant before the stream is passed to downstream components of the recycling system. A further need exists for an oil separator that goes beyond simple lubricant separation by removing other contaminants, most notably hexane derivatives, from the refrigerant stream. A related need exists for an refrigerant oil separator for use with refrigerant recycling machines that allows reverse flow of cleaned refrigerant through the recycling machine back to an air conditioning system without being re-contaminated by the contaminates collected in the oil separator. It is to an oil separator that satisfies these and other needs that the present invention is primarily directed.